Advertise TorchGeo Slack (#1549)

* Advertise TorchGeo Slack

* Add color and logo

.github/ISSUE_TEMPLATE/config.yml

@@ -3,3 +3,6 @@ contact_links:
   - name: ❓ Questions
     url: https://github.com/microsoft/torchgeo/discussions
     about: Ask questions or discuss ideas with other TorchGeo users
+  - name: 💬 Chat
+    url: https://join.slack.com/t/torchgeo/shared_invite/zt-22rse667m-eqtCeNW0yI000Tl4B~2PIw
+    about: Chat with fellow TorchGeo users and developers on Slack

README.md

@@ -7,17 +7,20 @@ The goal of this library is to make it simple:
 1. for machine learning experts to work with geospatial data, and
 2. for remote sensing experts to explore machine learning solutions.
 
-Testing:
-[![docs](https://readthedocs.org/projects/torchgeo/badge/?version=latest)](https://torchgeo.readthedocs.io/en/stable/)
-[![style](https://github.com/microsoft/torchgeo/actions/workflows/style.yaml/badge.svg)](https://github.com/microsoft/torchgeo/actions/workflows/style.yaml)
-[![tests](https://github.com/microsoft/torchgeo/actions/workflows/tests.yaml/badge.svg)](https://github.com/microsoft/torchgeo/actions/workflows/tests.yaml)
-[![codecov](https://codecov.io/gh/microsoft/torchgeo/branch/main/graph/badge.svg?token=oa3Z3PMVOg)](https://codecov.io/gh/microsoft/torchgeo)
+Community:
+[![slack](https://img.shields.io/badge/slack-join-purple?logo=slack)](https://join.slack.com/t/torchgeo/shared_invite/zt-22rse667m-eqtCeNW0yI000Tl4B~2PIw)
 
 Packaging:
 [![pypi](https://badge.fury.io/py/torchgeo.svg)](https://pypi.org/project/torchgeo/)
 [![conda](https://anaconda.org/conda-forge/torchgeo/badges/version.svg)](https://anaconda.org/conda-forge/torchgeo)
 [![spack](https://img.shields.io/spack/v/py-torchgeo)](https://spack.readthedocs.io/en/latest/package_list.html#py-torchgeo)
 
+Testing:
+[![docs](https://readthedocs.org/projects/torchgeo/badge/?version=latest)](https://torchgeo.readthedocs.io/en/stable/)
+[![style](https://github.com/microsoft/torchgeo/actions/workflows/style.yaml/badge.svg)](https://github.com/microsoft/torchgeo/actions/workflows/style.yaml)
+[![tests](https://github.com/microsoft/torchgeo/actions/workflows/tests.yaml/badge.svg)](https://github.com/microsoft/torchgeo/actions/workflows/tests.yaml)
+[![codecov](https://codecov.io/gh/microsoft/torchgeo/branch/main/graph/badge.svg?token=oa3Z3PMVOg)](https://codecov.io/gh/microsoft/torchgeo)
+
 ## Installation
 
 The recommended way to install TorchGeo is with [pip](https://pip.pypa.io/):